GB1024692A - Production of ferro-chrome alloys - Google Patents

Abstract

A ferro-chrome alloy, e.g. consisting of more than 50 to 75% Cr, 0.5 to 50% Si, trace to 10% C, with balance Fe and incidental impurities such as Mn, Al, P, S, is produced by first heating a mixture of finely divided FeO.Cr2O3 ore, e.g. passing a 60 B.S. sieve, and finely divided carbonaceous reducing agent at least comprising mainly coking coal of average swelling index at least 3, e.g. passing a 150 B.S. sieve, with or without a finely ground flux such as silica sand, e.g. at 600-1250 DEG C., to at least partially carbonize the coal and partially reduce the ore in the solid state, and then smelting the resulting mass to completely reduce the partially reduced ore to Fe-Cr alloy at least partly by means of the residual carbon in the mass. Before heating, the mixture is preferably formed into green pellets or briquettes incorporating moisture as a temporary binder, with or without bentonite, the pellets or briquettes being dried e.g. at 100-200 DEG C. After heating, pellets or briquettes are formed comprising cellular matrices of coke with interstitial partially reduced ore with or without flux. The smelting may be performed in a submerged arc electric furnace wherein the combustible gas produced-mainly CO-is burnt to provide for initial heating. Additional ore, carbonaceous reducing agent, or flux, in lumpy form if desired, may be added to the smelting charge. The reducing agent may include powdered anthracite, charcoal or coke.ALSO:Pellets or briquettes comprising cellular matrices of coke containing interstitial partially reduced finely divided, e.g. passing a 60 B.S. sieve, iron-chrome oxide ore, with or without finely ground flux such as silica sand, for smelting to produce ferro-chrome alloy, are formed by briquetting a finely divided mixture of FeO.Cr2O3 ore and carbonaceous reducing agent at least comprising mainly coking coal of average swelling index at least 3, e.g. passing a 150 B.S. sieve, with or without the flux and moisture as a temporary binder, preferably drying at 100-200 DEG C., and heating the green pellets or briquettes formed at 600-1250 DEG C. to at least partially carbonize the coal and partially reduce the ore in the solid state. Bentonite may be added to the mixture as a binder.